- Additional - see also Accessory
- Adduction contracture, hip or other joint - see Contraction, joint
- ADEM (acute disseminated encephalomyelitis) (postinfectious) 136.9 [323.61]
- Aden fever 061
- Adenasthenia gastrica 536.0
- Adenitis (see also Lymphadenitis) 289.3
- Adenoacanthoma (M8570/3) - see Neoplasm, by site malignant
- Adenoameloblastoma (M9300/0) 213.1
- Adenocarcinoma (M8140/3) - see also Neoplasm, by site, malignant
- Adenofibroma (M9013/0)
- Adenofibrosis
- Adenoiditis 474.01
- Adenoids (congenital) (of nasal fossa) 474.9
- Adenolipomatosis (symmetrical) 272.8
- Adenolymphoma (M8561/0)
- Adenoma (sessile) (M8140/0) - see also Neoplasm, by site, benign
- Adenomatosis (M8220/0)
- Adenomatous
- Adenomyoma (M8932/0) - see also Neoplasm, by site, benign
- Adenomyometritis 617.0
- Adenomyosis (uterus) (internal) 617.0
- Adenopathy (lymph gland) 785.6